Thermionic valve



Aug. 30, 1932. H; J. ROUND 1,874,355

Tamzuiomc VALVE Filed March 10, 1925 i E l i l 1 i I 1 1s 4 Al 4 V1 4INVENTOR HENRY J. ROUND ORNEY Patented Aug. 30, 1932 umenfisnms PATENTOFFICE HENRY .rosnrn nounnor Lonnoia; momma; Assrenoa T RADIOCORPORATION 01? AMEmcA, A coaronA'rron or DELAWARE ammonia VALVE Applation fi tdvllarch 10. .19 a 6 ,andin Great Britain I am, 1924. i

This invention relates to thermionic valves. When a valve is used eitherfor rectifying or for generating oscillations it is usually desirablethat it should have a large current 5 carrying capacity and lowresistance. The first re uisite can be obtained by employing a largelament; the second by arranging the filament as close as possible to theanode or grid. A long filament, however is weak latin erally and is aptto be deformed under the strong attraction from the anode. To overcomethis defect it has been suggested to employ a number of filaments inparallel but if this is done the magnetic forces between 1.3 thefilaments cause trouble.-

According to this invention I construct the cathode of a cylinder ofparallel wires or meshwork which is supported at one end by a diskcarried by a stem lying along the axis so of the cylinder and at theother end by a movable support which may conveniently comprise a ringcarried by a spider the centre of which can slide along'the stem,'aninsulating sleeve or bush being interposed between the spider and thestem. 7

Means may be provided for keeping the meshwork taut, for instance, I mayconnect the spider by springs to the stem through an insulator.

Preferably the stem is supported on a plate or cap fused on to the endof a short glass cylinder or ring of metal which is mounted on a longglass cylinder, and this again in turn is fused on to the anode. Theshort ring 5 of metal is connected by flexible metal to the ringsurrounding the stem.

This plate or cap and the short metal ring act as the input terminalsfor the filament current.

Thus two connections to the cathode come to the outside.

In a valve in which there is a grid the other end of the anode is fusedon to a glass cylinder, which is fused on to a metal plate or cap onwhich the grid is mounted.

V The invention is illustrated in the accorm V panying drawing, in which1 i Fig. 1 shows a, cathode in accordance with this invention; i 1, Fig.2 shows a modified form of cathode;

Fig.3 illustrates the invention as applied to a-rectifying valve; f fFig. 4 illustrates the invention as applied to an amplifying valve; and

, Fig. 5 shows adetail. I Referring to Fig. 1, 1 is a,central stemsupporting a metal disk 2 tolwhich one end of the wires 3; forming thecathode is secured, the otherend of the wires being attached to a metalring 4 integral with an electrically conducting spider 4, slidablymounted on the stem 1,,also electrically conducting. 5 is a sleeve ofinsulating material interposed between the spider 4 and stem 1.. Thewires 3 are kept taut by springs 6 attachedat one end to lugs 7 on thespider and at the'other end toan insulator on a pin 8 passing throughthe stem 1. Spacing wires 9 may be provided whichintermesh with thewires 3.

Referring to Fig. 2, similar parts have similar numerals. In this casethe wires 3 form a portion of a helix and are intermeshed, while thespider 4 ismaintained in such a position on the stem 1 by a screw 10that the wires 3 lie on a cylindrical surface; on becoming heated, thecurvature ofthe wires 3 g is altered to a slight extent only. Referringto Fig. 3, which shows a recti- 'fying valve, similar parts have similarnu merals, 11 is a cap providedwith a socket: 12 for receiving the stem1; 13 is a metal ring to which the wires 3 are electrically connected asshown at 3f and which is fused. to glass cylinders 14 and 15of'which'1fl isalso fused to the cap 11, and15 to'a cylindrical metalanode 16 whose other end is closed. 7

Fig. 4 shows an amplifying valve having a grid 17 secured to a metal cap18; =19 is a glasscylinder secured atone end to the cap .18 and at theother end towthe anode 16.

Fig. 5 shows a modified form of seal between the cap 11 and the metalring 13. Since the insulation 14 between the cap and ring has only towithstand the small potential difference due to the filament voltage, itmay be quite small and be formed of a glass ring, the cap 11 and metalring 13 terminating in thin metal rims, say of platinuIn.

Having described my invention what I claim-is:

1. A thermionic device, comprising an evacuated envelope, a metallic capclosing oneend thereof, a cathode comprising a metallic rod supported bysaid cap, a disk fixed to one end of said rod, a' metallic ring slid-'ably mounted on said rod and insulated therefrom, a filament comprisinga plurality of wires connected between said disk and said ring, andmeans connected with said metallic ring for applying tension to thefilament gaging said rod and said spider to move said spider along saidrod away from said disc to stretch said filaments between said disc andsaid spider.

4. A thermionic cathode comprising a metal rod, a transverse metal discfixed to said rod near one end, an insulating stud on said rod near theother end, a metal spider on said rod between said disc and said studand comprising a metal ring on the ends of arms projecting from a hub,an insulating bushing fixed in said hub and slidable along said rod, aplurality of filaments stretched side by side between the rim of saiddisc and said metal ring, and a tension spring anchored at one end tosaid stud and at the other end tosaid spider to pull said spider awayfrom said disc and maintain said filaments taut.

HENRY JOSEPH ROUND.

wires, an anode surrounding said cathode, a

metallic contact member forming a portion of said envelope, insulatingmeans between said metallic contact member and said metallic cap, andconducting means, connecting said metallic ring and said contact member.

2. In a thermionic device, the combination with an evacuated tubularenvelope having walls consisting of a tubular metal anode with a glassring hermetically sealed to each of its ends, a metal cap hermeticallysealed to one of said glass rings, a metal contact ring hermeticallysealed at one edge to the other of said glass rings, a'third glass ringadjoining and sealed to the other edge of said metal contact ring, and asecond metal cap hermetically sealed to said third glass ring, of atubular grid mounted on said first metal cap to project into saidenvelope inside of and concentric with said anode, a cathode comprisinga central metal rod mounted on and projecting from said second metal capinto said envelope concentric with said anode, a circular metal discmounted on and extending transversely of said rod near one end, a metalspider slidably mount-- ed on and insulated from said rod near the endand comprising a metal ring encircling 3. A thermionic cathodecomprising a metal rod, a transverse metal disc fixed to said rod nearone end, a metal spider having arms projecting from a hub insulated fromand slidably mounted on said rod near the other end thereof, a pluralityof electron emitting filaments each secured at one end to'the rim ofsaid disc and at the other end to said spider, and a resilient memberen- Elf

